Local number portability cross connect method

ABSTRACT

A method is provided to implement a subscriber local number portability migration request. The method includes sending a trigger signal to a cross-connect device to cause the cross-connect device to switch between a first communication channel and a second communication channel. The first communication channel is between an originating switch associated with a subscriber&#39;s directory number and a distribution frame. The second communication channel is between a porting switch and the distribution frame. The method also includes validating that the cross-connect device switched between the first communication channel and the second communication channel.

RELATED APPLICATION

The present application is a continuation application of U.S. patentapplication Ser. No. 10/777,392 entitled “Local Number Portability CrossConnect Switch Network”, which is a continuation of U.S. patentapplication Ser. No. 09/656,670 filed Sep. 7, 2000, now U.S. Pat. No.6,711,251, both of which are incorporated by reference herein in theirentirety.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to telecommunication methods,and more particularly, relates to a cross connect methods for enablinglocal number portability in an intelligent switched telecommunicationsnetwork.

BACKGROUND

Local Number Portability (LNP) allows telephone service subscribers toretain their same directory number, at the same location, when asubscriber changes from one local telephone service provider to another.Telephone number portability was mandated by the Telecommunications Actof 1996.

Telephone calls are routed from a calling subscriber to a calledsubscriber through the public switched telephone network. A centraloffice switch is used for connecting the subscriber telephone lines.Subscribers connected to a common switch, or End Office (EO) areassigned a unique directory number, commonly referred to as a telephonenumber. The format of the directory number is NXX-XXXX, where “N” refersto any digit except zero or one and “X” refers to any one of 10 digits.Directory numbers are assigned in blocks of ten thousand to each LocalExchange Carrier (LEC). The first three digits of the directory numberare referred to as the exchange code. Each exchange code corresponds toa particular switch or EO. The last four digits of a directory numberare referred to as the subscriber's line code. The United States is alsodivided into “area codes,” more technically referred as Numbering PlanArea (NPA) codes. Thus, each telephone subscriber is associated with aunique 10 digit directory number comprising the three digit NPA code,the three digit exchange code (NXX) plus a four digit line number(XXXX).

The area code and exchange code prefix is used to route the call to theserving End Office. At the End Office, the local switch routes the callto the subscriber's line, which is designated by the last four digits ofthe directory number. Thus, when a calling party places a telephonecall, the first six digits of the dial directory number uniquelyidentify the terminating switch for the telephone call. The originatingswitch relies on this relationship to determine the most efficientrouting path from the originating switch to the terminating switch atthe End Office. Specifically, each switch typically includes a databasethat cross-references the area code, exchange code prefixes (NPA-NXX) tothe various switches. The originating switch then routes the telephonecall to the correct terminating switch, which, in turn, further routesthe telephone call to the correct subscriber telephone line.

With the passage of the Telecommunications Act of 1996, more than onelocal telephone service provider in the same geographic area may installand maintain the switching equipment required to provide local telephoneservice. Indeed, their respective switches can be located in the samebuilding. Local telephone service subscribers can then change theirtelephone service providers by having the lines servicing their premisesdisconnected from their previous local telephone service provider andreconnected to their new local telephone service provider. Thisdisconnection and reconnection is referred to as a “cutover,” and maytake place at any point in the telephone line circuit to a subscriber'spremises. For example, a subscriber line may be cutover at the terminaljack located at the subscriber's premises, at the local telephoneservice provider's distribution frame, or at any other point in thecircuit. Local number portability requires that a subscriber anddirectory number be re-assigned from the switch associated with thepresent local telephone service provider to the switch associated withthe new local telephone service provider. In a local number portabilityenvironment, therefore, the area code-exchange code portion of adirectory number will not uniquely identify the switch servicing theline assigned to that directory number. Accordingly, additionaltelephone call routing procedures are required to allow an originatingswitch that initially receives a telephone call to determine the correctterminating switch. This is typically accomplished by a LNP databasethat cross-references individual portable directory numbers to thevarious switches.

Accordingly, in a LNP environment, originating stations throughout thepublic switched telephone network refer to their respective LNPdatabases to determine the terminating stations that service portedsubscriber telephone lines. Whenever a subscriber changes localtelephone service providers but wishes to maintain the same directorynumber, all of the LNP databases must be programmed with the portingsubscriber directory number and an identification code for the newterminating switch. Until the porting subscriber line is physicallycutover from the original terminating switch to the new terminatingswitch, telephone calls directed to the subscriber directory number mustbe routed to the prior telephone service provider's terminating switch.After the subscriber line has been cutover, however, telephone callsdirected to the subscriber's directory number must be routed to the newtelephone service provider's terminating switch. Timing problems,therefore, arise because the physical cutover of the subscriber lineoccurs at a particular time instant. The various LNP databases, on theother hand, cannot be reprogrammed at the same instant. Thus,subscribers may experience interruptions in phone service until the LNPdatabases can be updated to reflect the relationship between thesubscriber's directory number and the new telephone service provider'sterminating switch. In addition, coordinating the physical cutover anddatabase updating imposes scheduling demands upon service providerpersonnel. Thus, there exists a need for an improved system and methodfor enabling local number portability.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this invention reference should nowbe had to the embodiments illustrated in greater detail in theaccompanying figures and described below by way of examples of theinvention wherein:

FIG. 1 is a schematic block diagram of the present invention in acentral office environment.

FIG. 2 is a schematic block diagram of one embodiment of the LNPCCSaccording to the present invention.

FIG. 3 is a logic flow diagram of one method of implementing the LNPCCSof the present invention.

FIG. 4 is a logic flow diagram of another method of activating theLNPCCS of the present invention.

DETAILED DESCRIPTION

Referring now to FIG. 1, there is shown a schematic block diagram of oneembodiment of the present invention in a central office (CO)environment. The central office 10 is the site where the Local ExchangeCarrier's (LEC) equipment resides which routes calls to and fromcustomers served by the LEC. Telephone calls routed to the centraloffice 10 enter the building on communication line 11 and are directedto the Main Distribution Frame (MDF) 12. The three-digit exchange codeassociated with the incoming dial directory number is routed to thecorresponding LEC switch 14, and specifically, to that portion of theswitch corresponding to the subscriber's line code. As described above,in order to implement LNP, the physical routing of a subscriber linemust be cutover from the originating switch such as LEC switch 14 to theported switch such as the Competitive Local Exchange Carrier (CLEC)switch 18. The Local Number Portability Cross Connect Switch (LNPCCS) 16accomplishes the cutover by switching the connection to the MDF from theoriginating switch to the ported switch upon receiving a predeterminedsignaling sequence as described in more detail below.

Referring now to FIG. 2, there is shown a schematic block diagram of oneembodiment of the LNPCCS 30 according to the present invention. TheLNPCCS 30 comprises an Originating Dial Tone (ODT) port 32 for receivingthe line connection from the originating switch associated with asubscriber's directory number, a Ported Dial Tone (PDT) port 34 forreceiving the line connection from the porting switch associated withthe subscriber's directory number, and a Main Distribution Frame (MDF)port 36 for connecting the LNPCCS 30 to the Main Distribution Frameassociated with the originating switch and the ported switch. Each ofthe ports 32, 34, and 36 include terminal blocks for the tip and ringportions of the twisted wire pair. The LNPCCS 30 may be installed in theCentral Office wiring room on the MDF. The wiring associated with eachof the ports 32, 34, 36 may support 48 volts DC (normal telephone linepower) and 96 volts AC (telephone ringing generator).

The LNPCCS 30 also includes a switch 44 connecting the ODT port 32 andPDT port 34 to the MDF port 36, and a controller 40 in operativecommunication with the switch 44, ODT port 32, PDT port 34 and MDF port36. The switch is connected to the ports such that the ODT path isnormally closed and the PDT path is normally open. In other words, thedefault switch connection is a closed loop from the ODT port 32 to theMDF port 36 and an open loop between the PDT port 34 and the MDF port36. The switch 44 may be a double-pole, double-throw relay-type switchsuch as is available from NEC Corp. as model ED2-5T. Light emittingdiodes (LEDs) 46, 48 indicate the state of the switch. The controller 40includes a processor 42 and associated memory 43. An example of asuitable controller is model PIC16C505 available from Microchip Corp.The controller 40 and “Arm” LED 46 are line powered from the ODT sidebefore the trigger signal is received by the controller. After receiptof the trigger signal, the “Trip” LED 48 and controller 40 are linepowered from the PDT side of the device.

The “Arm” LED 46 is active when the ODT port 32 and MDF port 36 arewired and the switch 44 is ready to receive the trigger signal. Thetrigger signal may be a Mechanized Loop Testing (MLT) tracking tone,which can be received from either the ODT port 32 or the PDT port 34.When the trigger signal is received, the “Trip” LED 48 is activated toalert an operator of the state of the switch.

A power supply 50 is also included to provide alternative power to theswitch 44 and controller 40. Power may be supplied to the ODT side ofthe device until the switch is activated and the unit is later removedfrom the MDF. A manual override in the form a reset switch 52 is alsoprovided to “build back” or re-establish the original connection fromthe ODT port 32 to the MDF port 36 after the switch 44 has beenactivated. In such cases, the power supply 50 drives the switch 44 toclose the ODT path and open the PDT path to the MDF.

Referring now to FIG. 3, there is shown a logic flow diagram of onemethod of implementing the LNPCCS of the present invention. The methodof implementing local number portability with the LNPCCS begins in step300 when a CLEC submits an LNP migration request to the telephoneservice subscriber's present local exchange carrier. The migrationrequest represents the subscriber's desire to change service providers.In step 302, the LEC creates an internal service order to process theCLEC's LNP migration request. At this time, a due date for the LNPmigration is decided upon between the CLEC and the customer, and theCLEC and LEC.

In step 304, the central office technician wires the LNPCCS “in line” tothe existing telephone service. This is accomplished by wiring in thejumper from the original office equipment to the originating dial tone(ODT) port on the LNPCCS device, and the jumper from the maindistribution frame (MDF) port to the vertical frame or MDF, therebycompleting the original circuit path. These connections are made byinserting the “tip” and “ring” wire pair into the respective ODT and MDFtip and ring ports on the LNPCCS device. This process is also repeatedfor the tip and ring wire pair for the ported dial tone (PDT) port tothe CLEC's switching equipment.

In step 306, the central office technician validates that the LNPCCSdevice is in the “armed” position, which is indicated by the red lightemitting diode (LED). When the armed LED is active, it indicates to thetechnician that the LNPCCS has been properly connected in line with thecustomer's original circuit path. The central office technician can thennotify the local operating center that the switch has been deployed suchas in step 308.

Once the LNPCCS is armed and ready, the local operating center activatesthe device remotely on the service order due date, in step 310. Theactivation process begins in step 312 by testing for the presence of apredetermined resistance on the ODT side when the switch is in the ODTstate. The line may be tested for an 18 kOhm short from ODT side. Atthis time, the processor and the ODT LED are line powered from the ODTside of the circuit before the activation tone is received. In step 314,a check is made as to whether the termination value has been validated.Specifically, the tip to ring resistance of the ODT port when the switchis in the. ODT to MDF state is tested to detect a predeterminedresistance value, which, in this example, is 18 kOhm. If not, in step316, the central office is contacted and the request made to check theintegrity of the connection or manually cutover the service migrationrequest.

If the line has been validated, in step 318, the device is switched bysignaling a predetermined tone from either the ODT or PDT side of thedevice to trip the LNPCCS from the armed position to the “tripped”position. The signaling tone may be a Mechanized Loop Testing (MLT)tracking tone of approximately 10-second duration transmitted on the ODTside of the device. The MLT tone may be a 577.5 Hz signal of 3.25 Vamplitude that is pulsed on for 100 ms and off for 100 ms for a pulsetrain duration of at least two seconds. The signal is delivered betweenthe tip and ring connections. This signaling tone is desirable becauseit is a standardized signal available to all telephone serviceproviders, yet is unique enough that a device is unlikely to beaccidentally or prematurely tripped by normal data or voice traffic overthe original subscriber loop. After reception of the signaling tone, thegreen tripped LED is powered from the PDT side of the device. Inaddition, subsequent triggering tones can be used to toggle the state ofthe switch.

To ensure the device has been properly activated, in step 320, theoriginal service is re-tested to validate that the termination value haschanged by a predetermined amount. The tip to ring termination value haschanged from 18 kOhms to 17.5 kOhms on the ODT port when the switch isin the PDT to MDF state. If the termination value has not changed, asindicated in step 322, the central office is again contacted in step 324to troubleshoot these device connections. Otherwise, in step 326, thelocal operating center completes the service order request by modifyingthe CLEC database records to indicate the CLEC's terminating switch forthe associated customer's directory number.

As shown in step 328, the LNPCCS device is removed from the circuitsafter a predetermined period of time and the circuit change ishard-wired without disrupting service, such that the LNPCCS unit is nowavailable for reuse with other service order requests.

Referring now to FIG. 4, there is shown a logic flow diagram of anothermethod of activating the LNPCCS of the present invention. The logicdiagram of FIG. 4 describes one example of a specific MLT tracking toneimplementation. At the start of the logic, it is assumed that the LNPCCSis correctly connected between the MDF and ODT and PDT switches. At thispoint, the LNPCCS is line powered from the ODT side of the device by the48 VDC line voltage. This power is regulated by the power supply to 5.0VDC at 3.75 mA. The logic begins in step 400 by initializing all programvariables. This includes testing the switch connection to insure thatthe LNPCCS is in the ODT to MDF state, and activating the “Armed” LED.In step 402, the controller enters a “sleep” mode and waits for theactivation signal.

In step 404, unless the Reset button on the device is activated, or atone received, the controller remains in the sleep mode. Otherwise, instep 406, if the Reset button is activated for a predetermined period oftime, the switch is activated to toggle the port (either ODT or PDT)connected to the MDF as shown in step 408.

If a tone is detected in step 404, steps 410 through 426 determine ifthe tone is the desired signaling tone. In this example, the desiredsignaling tone is an MLT tone consisting of a 577.5 Hz audio tone with a5 Hz cadence. Accordingly, in steps 410 and 414, the “on” portion of thedesired pulse train is detected and validated. Similarly, in steps 416through 422, the “off” portion of the desired pulse train is detectedand validated. The validity of the overall signal is assured in steps424 and 426 by repeated detection of the predetermined signal for athreshold number of cycles. If the signal has been validated, the logiccontinues to step 428 where the switch is toggled to change the port(ODT or PDT) connected to the MDF. The devices then pauses for apredetermined period of time, during which time, the device power can bechanged from the ODT side to the PDT side, for example.

While the invention has been described in connection with one or moreembodiments, it is to be understood that the specific mechanisms andtechniques which have been described are merely illustrative of theprinciples of the invention, numerous modifications may be made to themethods and apparatus described without departing from the spirit andscope of the invention as defined by the appended. claims.

1. A method comprising: sending a trigger signal to a cross-connectdevice to cause the cross-connect device to switch between a firstcommunication channel and a second communication channel, wherein thefirst communication channel is between an originating switch associatedwith a subscriber's directory number and a distribution frame, and thesecond communication channel is between a porting switch and thedistribution frame; and validating that the cross-connect deviceswitched between the first communication channel and the secondcommunication channel.
 2. The method of claim 1, wherein validating thatthe cross-connect device switched between the first communicationchannel and the second communication channel comprises determiningwhether the first communication channel has been deactivated.
 3. Themethod of claim 1, wherein validating that the cross-connect deviceswitched between the first communication channel and the secondcommunication channel comprises determining whether a predeterminedresistance is detected on the first communication channel.
 4. The methodof claim 1, further comprising validating that the first communicationchannel is active at the cross-connect device before sending the triggersignal.
 5. The method of claim 4, wherein validating that the firstcommunication channel is active at the cross-connect device beforesending the trigger signal comprises determining whether a predeterminedresistance is detected on the first communication channel.
 6. The methodof claim 5, wherein validating that the cross-connect device switchedbetween the first communication channel and the second communicationchannel comprises determining whether a resistance value detected on thefirst communication channel after sending the trigger signal has changedby a predetermined amount.
 7. The method of claim 1, wherein the triggersignal comprises a mechanized loop testing tracking tone sent via thesecond communication channel.
 8. The method of claim 1, wherein thetrigger signal comprises a mechanized loop testing tracking tone sentvia the first communication channel.
 9. The method of claim 1, furthercomprising updating a database to associate the subscriber's directorynumber with the ported switch after sending the trigger signal.
 10. Themethod of claim 1, further comprising sending a second trigger signal tothe cross-connect device to cause the cross-connect device to switchbetween the second communication channel and the first communicationchannel.
 11. A method comprising: receiving a trigger signal at across-connect switch; and switching between a first communicationchannel and a second communication channel after receiving the triggersignal, wherein the first communication channel connects between anoriginating switch associated with a subscriber's directory number and adistribution frame, and the second communication channel connectsbetween a porting switch and the distribution frame.
 12. The method ofclaim 11, further comprising activating an indicator at thecross-connect switch to show which of the first and second communicationchannels is active.
 13. The method of claim 11, wherein the triggersignal is received via the originating switch.
 14. The method of claim11, wherein the trigger signal is received via the porting switch. 15.The method of claim 11, wherein switching between the firstcommunication channel and the second communication channel comprisesdeactivating the first communication channel and activating the secondcommunication channel.
 16. The method of claim 11, wherein the triggersignal comprises a mechanized loop testing tracking tone.
 17. The methodof claim 11, further comprising receiving a reset signal and switchingbetween the second communication channel and the first communicationchannel in response to the reset signal.
 18. A cross-connect devicecomprising: a plurality of ports to connect to a distribution frame, anoriginating switch and a porting switch; and a controller to receive atrigger signal via at least one of the plurality of ports and todeactivate a first communication channel and to activate a secondcommunication channel after receiving the trigger signal.
 19. The deviceof claim 18, wherein the controller is powered via the firstcommunication channel when the first communication channel is active andis powered via the second communication channel when the secondcommunication channel is active.
 20. The device of claim 18, wherein thecontroller is powered by an onboard power supply.